JP2004205659A - Optical switch device and light transmission system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical switch device that can reduce influence on optical signals passing through other input/output ports when an input/output optical path of an input/output port is switched. <P>SOLUTION: The optical switch device has an optical switch array 6 that changes over the input/output optical path of a plurality of input/output optical fibers. The optical switch array 6 has a base plate 8 on which a cantilever extension 11 is held. At the tip end of the cantilever extension 11, there is installed an annular support 12 on which a movable mirror 7 is supported tiltably. The movable mirror 7 reflects an optical signal from any one input/output optical fiber to other input/output optical fiber. At the tip end of the cantilever extension 11, a comb-teeth part 14 is installed. On the upper face of the base plate 8, there are arranged electrodes 15a, 15b for tilting the movable mirror 7 relative to the annular support 12 and an electrode 16 for moving the movable mirror 7 in the direction different from its tilting direction. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical switch device and an optical transmission system used in Wavelength Division Multiplexing (WDM) optical communication and the like.
[0002]
[Prior art]
As an optical switch device used in a WDM optical communication system, for example, there is a wavelength switching switch described in Non-Patent Document 1. This wavelength changeover switch has a configuration in which a plurality of input / output ports formed of optical fibers and lenses, a diffraction grating, and a MEMS mirror are combined, thereby enabling miniaturization and cost reduction.
[0003]
[Non-patent document 1]
OFC 2002 Postdeadline Papers, FB7-1, Wavelength-selective 1 × 4 switch for 128 WDM channels at 50 GHzspacing
[0004]
[Problems to be solved by the invention]
However, the conventional technique has the following problems. That is, since the MEMS mirror is driven only in the direction of switching the input / output optical path of the input / output port, when the input / output optical path of the input / output port is switched, the optical signal reflected by the MEMS mirror crosses the adjacent input / output port. Sometimes. In this case, since unnecessary light enters the adjacent input / output port, the transmission quality of the optical signal passing through the input / output port deteriorates.
[0005]
An object of the present invention is to provide an optical switch device and an optical transmission system that can reduce the influence on an optical signal passing through another input / output port when switching the input / output optical path of the input / output port.
[0006]
[Means for Solving the Problems]
The present invention relates to an optical switch device comprising: a plurality of input / output ports for inputting / outputting an optical signal; and switch means for switching an input / output optical path of the input / output port. An optical component for reflecting an optical signal input from the input / output port toward another input / output port, first driving means for driving the optical component so as to switch the input / output optical path of the input / output port, Second driving means for driving the optical component so as to move between a position for reflecting the light toward the input / output port and a position for reflecting the optical signal in a direction shifted from the direction toward the input / output port. It is a feature.
[0007]
In such an optical switch device of the present invention, when the input / output optical path of the input / output port is switched, first, the optical signal is reflected from the position (normal position) where the optical signal is reflected in the direction toward the input / output port by the second driving means. The optical component is moved to a position where the signal is reflected in a direction shifted from a direction toward the input / output port (a retreat position). Subsequently, the first driving unit drives the optical component such that the input / output optical path of the input / output port is switched. After that, the optical component is returned from the retracted position to the normal position by the second driving means. After the optical component is moved to the retreat position in advance by the second driving means in this way, the optical component is driven by the first driving means to switch the input / output optical path of the input / output port. During the switching, the optical signal reflected by the optical component does not cross other input / output ports that are not switching targets. Therefore, since light leaking to another input / output port is reduced, the influence on an optical signal passing through the input / output port can be reduced.
[0008]
Preferably, the apparatus further comprises an optical demultiplexing element for demultiplexing the wavelength-division multiplexed optical signal input from the input / output port for each wavelength, and the switch means includes an optical component corresponding to each signal light demultiplexed for each wavelength. Have multiple. As a result, the optical switch device of the present invention can be used as a wavelength switching switch, so that an optical ADM (Add Drop Multiplexer) for ADD or DROP of a signal of an arbitrary wavelength from among wavelength-multiplexed optical signals has a simple configuration. It becomes feasible.
[0009]
Preferably, the optical component is provided on the cantilever supported by the base body so as to be tiltable, the first driving unit is a unit for tilting the optical component with respect to the cantilever, and the second driving unit is Means for moving the optical component in a direction different from the tilting direction of the optical component. This makes it possible to simplify the structure of the switch means having the optical component, the first drive means, and the second drive means.
[0010]
At this time, preferably, the first driving means has a first electrode provided on the base, and a first voltage source for supplying a voltage to the first electrode, and the second driving means is provided on the base. It has a second electrode and a second voltage source that supplies a voltage to the second electrode. In this case, since the optical component is driven by electrostatic force, almost no current flows and power saving can be achieved.
[0011]
Further, the present invention provides an optical switch device including a plurality of input / output ports for inputting / outputting an optical signal and a switch for switching an input / output optical path of the input / output port, wherein the switch means An input / output optical path of an input / output port is switched so that an optical signal guided to any one of the input / output ports does not cross another input / output port.
[0012]
In this way, when switching the input / output optical path of the input / output port, by configuring so that the optical signal does not cross other input / output ports that are not switching targets, light leaking to other input / output ports is reduced. The influence on the optical signal passing through the input / output port can be reduced.
[0013]
Preferably, the switching time of the input / output optical path of the input / output port is 10 ms or less. Accordingly, when the input / output optical path of the input / output port is switched, light is more unlikely to leak to another input / output port that is not a switching target, so that the influence on the optical signal passing through the input / output port can be further reduced. .
[0014]
Also, preferably, when switching the input / output optical path of the input / output port, the crosstalk to another input / output port is -25 dB or less. As a result, there is almost no effect on optical signals passing through other input / output ports that are not switching targets.
[0015]
An optical transmission system according to the present invention includes the above optical switch device. Thus, as described above, when switching the input / output optical path of the input / output port in the optical switch device, it is possible to reduce the influence on the optical signal passing through another input / output port that is not a switching target.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of an optical switch device and an optical transmission system according to the present invention will be described with reference to the drawings.
[0017]
FIG. 1 and FIG. 2 are schematic structural views showing an embodiment of the optical switch device according to the present invention. In each drawing, an xyz rectangular coordinate system and an xy'z 'rectangular coordinate system are shown for convenience of explanation. FIG. 1 is a diagram when the optical switch device is viewed in the y-axis and y′-axis directions, and FIG. 2 is a diagram when the optical switch device is viewed in the x-axis direction.
[0018]
In each figure, the optical switch device 1 of the present embodiment has a plurality of input / output optical fibers 2a to 2f, an array lens 3, a diffraction grating 4, a lens 5, and an optical switch array 6. . An xyz orthogonal coordinate system is used in the optical system between the input / output optical fibers 2a to 2f and the diffraction grating 4, and an xy'z 'orthogonal coordinate system is used in the optical system between the diffraction grating 4 and the optical switch array 6. Is used.
[0019]
The input / output optical fibers 2a to 2f are input / output ports for inputting / outputting multiplexed optical signals (wavelength multiplexed optical signals) of, for example, four wavelengths λ _{1 to} λ ₄ , and are arranged in parallel in the z-axis direction. . Here, the input / output optical fiber 2c is used as a common input port, the input / output optical fiber 2d is used as a common output port, the input / output optical fibers 2a and 2e are used as Add ports, and the input / output optical fibers 2b and 2f are used. Is used as a Drop port.
[0020]
The array lens 3 collimates the optical signals input from the input / output optical fibers 2a, 2c, and 2e and outputs the collimated optical signals to the diffraction grating 4, and condenses the optical signals from the diffraction grating 4 to output the input / output optical fibers 2b and 2b. Output to 2d and 2f.
[0021]
The diffraction grating 4 diffracts the wavelength multiplexed signal light from the array lens 3 at a diffraction angle corresponding to each of the wavelengths λ _{1 to} λ ₄ to separate the wavelength multiplexed signal light into the wavelengths λ ₁ to λ _4. Output to the lens 5. Although the diffraction grating 4 in the drawing is of a transmission type, a reflection type diffraction grating may be used.
[0022]
Lens 5 outputs the optical signal of the diffraction grating 4 at demultiplexed wavelength lambda ₁ to [lambda] every ₄ to the optical switch array 6 is focused, diffracted collimates the optical signal from the optical switch array 6 grating 4 is output.
[0023]
The optical switch array 6 has movable mirrors 7a to 7d (hereinafter, sometimes collectively referred to as a movable mirror 7) for reflecting optical signals of the respective wavelengths λ _{1 to} λ ₄ collected by the lens 5, respectively. The input and output optical paths of the output optical fibers 2a to 2f are switched.
[0024]
FIG. 3 is a plan view showing a part of the optical switch array 6, and FIG. 4 is a sectional view taken along line IV-IV of FIG. In each of the drawings, the optical switch array 6 has a substrate 8 made of Si or the like, and a plurality of actuator units 9 formed on the substrate 8 using a micro electro mechanical system (MEMS) technology.
[0025]
Each actuator section 9 has a cantilever 11 supported on the upper surface of the substrate 8 via a spacer 10, and an annular support section 12 is provided at a distal end portion of the cantilever 11. The movable mirror 7 is supported by the annular support portion 12 via hinges 13 on both sides. The hinge 13 extends in the longitudinal direction of the cantilever 11, whereby the movable mirror 7 can be tilted with respect to an axis (y 'axis) parallel to the longitudinal direction of the cantilever 11 (see FIG. 6). At the tip of the cantilever 11, a comb tooth portion 14 is provided.
[0026]
As shown in FIG. 5, a pair of substantially semicircular electrodes 15a and 15b for tilting the movable mirror 7 with respect to the annular support portion 12 is provided on a portion of the upper surface of the substrate 8 facing the movable mirror 7. Is provided. A comb-shaped electrode for moving the movable mirror 7 in a direction different from the above-mentioned tilting direction of the movable mirror 7 by bending the cantilever 11 is provided on the upper surface of the substrate 8 in the vicinity of the comb teeth 14. 16 are provided.
[0027]
Such an actuator section 9 is formed of, for example, conductive Si. The reflecting surface of the movable mirror 7 is coated with, for example, Au so that the light from the lens 5 is almost totally reflected.
[0028]
The cantilever 11 and the electrodes 15a and 15b are connected via a voltage source 17, and a voltage is supplied to the electrodes 15a and 15b by the voltage source 17 so that the movable mirror 7 and the electrodes 15a and 15b are connected. The movable mirror 7 is tilted with respect to the annular support portion 12 of the cantilever 11 by generating an electrostatic force.
[0029]
At this time, when the voltage applied to the electrodes 15a and 15b is zero, the movable mirror 7 is in a state parallel to the annular support portion 12, as shown in FIG. In this state, the movable mirror 7 reflects the optical signal from the input / output optical fiber (common incident port) 2c toward the input / output optical fiber (common output port) 2d.
[0030]
On the other hand, when a predetermined voltage is applied to the electrode 15a, as shown in FIG. 6B, the portion of the movable mirror 7 on the electrode 15a side is attracted to the electrode 15a by the electrostatic force generated between the movable mirror 7 and the electrode 15a. Then, the movable mirror 7 is tilted with respect to the annular support portion 12. In this state, the movable mirror 7 reflects an optical signal from the input / output optical fiber (common incident port) 2c toward the input / output optical fiber (Drop port) 2f.
[0031]
When a predetermined voltage is applied to the electrode 15b, as shown in FIG. 6C, an electrostatic force generated between the movable mirror 7 and the electrode 15b causes the portion of the movable mirror 7 on the electrode 15b side to be attracted to the electrode 15b. Then, the movable mirror 7 tilts in the opposite direction with respect to the annular support portion 12. In this state, the movable mirror 7 reflects the optical signal from the input / output optical fiber (common incident port) 2c toward the input / output optical fiber (Drop port) 2b.
[0032]
The cantilever 11 and the electrode 16 are connected via a voltage source 18, and a voltage is supplied to the electrode 16 by the voltage source 18 to generate an electrostatic force between the comb tooth portion 14 and the electrode 16. Then, the front end portion of the cantilever 11 is bent downward.
[0033]
At this time, when the voltage applied to the electrode 16 is zero, the cantilever 11 is in a state of extending straight as shown in FIG. In this state, the movable mirror 7 transmits an optical signal guided from the input / output optical fibers 2a, 2c, and 2e through the array lens 3, the diffraction grating 4, and the lens 5 to the lens 5, the diffraction grating 4, and the array lens 3. At a normal position where the light is reflected in a direction toward the input / output optical fibers 2b, 2d, and 2f through the optical fiber.
[0034]
On the other hand, when a predetermined pulse voltage is applied to the electrode 16, as shown in FIG. 7, the comb tooth 14 is attracted to the electrode 16 by the electrostatic force generated between the comb tooth 14 and the electrode 16, and the cantilever 11 Is bent downward, whereby the movable mirror 7 moves in a direction different from the tilting direction of the movable mirror 7 (see FIG. 6). Thereby, the movable mirror 7 converts the optical signal guided from the input / output optical fibers 2a, 2c, 2e through the array lens 3, the diffraction grating 4, and the lens 5 from the direction toward the input / output optical fibers 2b, 2d, 2f. Move to the retract position where the light is reflected in the shifted direction.
[0035]
Next, the operation of the optical switch device 1 configured as described above will be described. The wavelength-division multiplexed optical signal input from the input / output optical fiber (common incident port) 2c is collimated by the array lens 3, is incident on the diffraction grating 4, and is demultiplexed for each of the wavelengths λ _{1 to} λ ₄ . The optical signals of the respective wavelengths λ _{1 to} λ ₄ are reflected by the movable mirrors 7 a to ₇ d of the optical switch array 6 while being collected by the lens 5.
[0036]
At this time, when the voltages applied by the voltage sources 17 and 18 of the optical switch array 6 are zero, the positions (postures) of the movable mirrors 7a to 7d are the normal positions as shown in FIG. The tilt angle of 7d is 0 degree as shown in FIG.
[0037]
In this case, the optical signals of the respective wavelengths λ _{1 to} λ ₄ reflected by the movable mirrors _{7 a to} 7 d are incident on the diffraction grating 4 and multiplexed while being collimated by the lens 5. Then, the multiplexed optical signal is output from an input / output optical fiber (common output port) 2d while being collected by the array lens 3. Thus, at the time of a power failure, the wavelength multiplexed optical signal input from the input / output optical fiber 2c is output from the input / output optical fiber 2d as it is.
[0038]
Here, when the wavelength switching so as to output from only the input and output optical fiber (Drop port) 2b optical signal, for example having a wavelength lambda ₄ of the wavelength-multiplexed optical signal input from the input and output optical fibers 2c, first wavelength In the actuator section 9 having the movable mirror 7d for reflecting the optical signal of λ ₄ , a pulse voltage is applied to the electrode 16 by the voltage source 18. Then, as shown in FIG. 7, the distal end side of the cantilever 11 of the actuator section 9 bends downward, and the movable mirror 7d moves from the normal position to the standby position. Thereby, the optical axis of the optical signal of wavelength λ ₄ reflected by the movable mirror 7 d is shifted from the optical axis of the optical signal of wavelengths λ ₁ to ₃ reflected by the movable mirror 7 d. Therefore, the optical signal of the wavelength λ ₄ reflected by the movable mirror 7d is not incident on the lens 5 and does not reach the input / output optical fiber 2d.
[0039]
In this state, in the actuator section 9 having the movable mirror 7d, a predetermined voltage is applied to the electrode 15b by the voltage source 17 and the movable mirror 7d is tilted in the direction shown in FIG. _The input / output optical fiber 2b is selected as the output port of the optical signal of No. ₄ .
[0040]
Subsequently, the voltage applied to the electrode 16 is set to zero. Then, the cantilever 11 returns to the initial state as shown in FIG. 4 by the urging force, and the movable mirror 7d returns from the standby position to the normal position. In this case, the optical signal of the wavelength λ ₄ reflected by the movable mirror 7 d is collimated by the lens 5, diffracted by the diffraction grating 4 and output from the input / output optical fiber 2 b while being condensed by the array lens 3. Is done.
[0041]
By the way, when the actuator section 9 does not have the comb teeth section 14, the electrode 16, and the voltage source 18, in the above-described wavelength switching, the movable mirror 7d is kept in the normal position shown in FIG. The tilt angle will change. That is, while the optical signal of wavelength λ ₄ reflected by the movable mirror 7 d is incident on the input / output optical fiber 2 d, the output optical path of the optical signal of wavelength λ ₄ is transmitted from the input / output optical fiber 2 d to the input / output optical fiber 2 b. Will be able to switch.
[0042]
In this case, since the optical signal of the wavelength λ ₄ reflected by the movable mirror 7d crosses the input / output optical fiber (common incident port) 2c between the input / output optical fibers 2d and 2b, it is unnecessary for the input / output optical fiber 2c. An optical signal enters. Therefore, the optical signal passing through the input / output optical fiber 2c is affected, and the transmission quality is significantly deteriorated.
[0043]
On the other hand, in the present embodiment, the movable mirror 7d is moved from the normal position shown in FIG. 4 to the retracted position shown in FIG. 7, and the tilt angle of the movable mirror 7d is changed in that state. when switching the output path to the optical fiber 2b, the optical signal of wavelength lambda ₄ reflected by the movable mirror 7d is never cross the input and output optical fiber 2c. Therefore, since unnecessary light leaking into the input / output optical fiber 2c is almost eliminated, deterioration of the transmission quality of the optical signal passing through the input / output optical fiber 2c can be prevented.
[0044]
At this time, in order to more reliably prevent light from leaking into the input / output optical fiber 2c, the switching time of the input / output optical path is preferably 10 ms or less. Further, when switching the input / output optical path, the intensity of the optical signal leaking to the input / output optical fiber 2c (crosstalk to the input / output optical fiber 2c) is preferably -25 dB or less.
[0045]
FIG. 8 shows a configuration of an optical ADM as an example of an optical transmission system including the optical switch device 1 described above.
[0046]
In FIG. 1, an optical ADM 20 has the optical switch device 1 described above, and a multiplexer 21 is connected to the input / output optical fiber 2 c of the optical switch device 1, and the input / output optical fiber 2 d of the optical switch device 1 A duplexer 22 is connected. The multiplexer 21 multiplexes the optical signals of each wavelength and guides them to one input / output optical fiber 2c. The demultiplexer 22 demultiplexes a plurality of optical signals having different wavelengths transmitted through one input / output optical fiber 2d for each wavelength. Further, add / drop multiplexers 23 are connected to the input / output optical fibers 2a and 2e of the optical switch device 1, respectively, and a drop splitter 24 is connected to the input / output optical fibers 2b and 2f of the optical switch device 1. Each is connected.
[0047]
By providing the optical switch device 1 in this manner, it is not necessary to configure the optical ADM using a large number of m × n optical switches. This makes it possible to reduce the size, simplification, and cost of the optical ADM.
[0048]
Note that the present invention is not limited to the above embodiment. For example, in the above embodiment, a mirror is used as an optical component for reflecting an optical signal from the lens 5, but a prism may be used instead of the mirror.
[0049]
In the above embodiment, the electrodes 15a, 15b and the electrodes 16 are provided on the substrate 8, and the movable mirror 7 is driven by electrostatic force. However, the movable mirror 7 may be driven by using an electromagnetic force. .
[0050]
Further, in the above embodiment, the plurality of input / output ports for inputting / outputting an optical signal are configured by optical fibers, but the plurality of input / output ports may be configured by a planar waveguide.
[0051]
In the above embodiment, the optical switch device is used for an optical ADM. However, the optical switch device of the present invention can be applied to an optical multiplexer / demultiplexer or the like. Further, the optical switch device of the present invention is not limited to the wavelength switch, but is applicable as long as it switches input / output optical paths of input / output ports.
[0052]
【The invention's effect】
According to the present invention, the first driving means for driving the optical component so as to switch the input / output optical path of the input / output port, the position for reflecting the optical signal in the direction toward the input / output port, and the optical signal toward the input / output port The second driving means for driving the optical component so as to move between a position where the light is reflected in a direction deviated from the direction is provided. The effect on the optical signal passing through the output port can be reduced.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing one embodiment of an optical switch device according to the present invention, and is a diagram when the optical switch device is viewed in the y-axis and y′-axis directions.
FIG. 2 is a schematic configuration diagram showing one embodiment of the optical switch device according to the present invention, and is a diagram when the optical switch device is viewed in the x-axis direction.
FIG. 3 is a plan view showing a part of the optical switch array shown in FIGS. 1 and 2;
FIG. 4 is a sectional view taken along line IV-IV of FIG. 3;
FIG. 5 is a plan view of the substrate shown in FIG. 3;
FIG. 6 is a cross-sectional view showing a state where the movable mirror is tilted with respect to the annular support portion.
FIG. 7 is a sectional view showing a state in which a movable mirror is moved by bending a cantilever in FIG.
FIG. 8 is a configuration diagram showing an optical ADM as an example of an optical transmission system including the optical switch device shown in FIGS. 1 and 2.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Optical switch device, 2a-2f ... Input / output optical fiber (input / output port), 3 ... Array lens, 4 ... Grating (optical demultiplexing element), 5 ... Lens, 6 ... Optical switch array (switch means), 7, 7a-7d: movable mirror (optical component), 8: substrate (base), 11: cantilever, 12: annular support, 13: hinge, 14: comb tooth, 15a, 15b: electrode (first) Electrode, first drive means), 16 ... electrode (second electrode, second drive means), 17 ... voltage source (first voltage source, first drive means), 18 ... voltage source (second voltage source, second drive) Driving means), 20 ... optical ADM (optical transmission system).

Claims (8)

An optical switch device comprising: a plurality of input / output ports for inputting / outputting an optical signal; and switch means for switching input / output optical paths of the input / output ports.
The switch means,
An optical component that reflects an optical signal input from any of the input / output ports of the plurality of input / output ports toward another input / output port;
First driving means for driving the optical component so as to switch an input / output optical path of the input / output port;
A second drive for driving the optical component so as to move between a position for reflecting an optical signal in a direction toward the input / output port and a position for reflecting an optical signal in a direction deviated from the direction toward the input / output port; And an optical switch device. Further comprising an optical demultiplexing element for demultiplexing the wavelength multiplexed optical signal input from the input / output port for each wavelength,
2. The optical switch device according to claim 1, wherein said switch means has a plurality of said optical components corresponding to each signal light demultiplexed for each wavelength. The optical component is provided to be tiltable on a cantilever supported by the base,
The first driving means is means for tilting the optical component with respect to the cantilever,
The optical switch device according to claim 1, wherein the second driving unit is a unit that moves the optical component in a direction different from a tilt direction of the optical component. The first driving unit has a first electrode provided on the base, and a first voltage source for supplying a voltage to the first electrode,
4. The optical switch device according to claim 3, wherein the second driving unit includes a second electrode provided on the base, and a second voltage source for supplying a voltage to the second electrode. An optical switch device comprising: a plurality of input / output ports for inputting / outputting an optical signal; and switch means for switching an input / output optical path of the input / output port.
The switch means switches an input / output optical path of the input / output port so that an optical signal guided to any one of the input / output ports does not cross another input / output port. Optical switch device. The optical switch device according to claim 1, wherein a switching time of an input / output optical path of the input / output port is 10 ms or less. The optical switch device according to claim 1, wherein when switching an input / output optical path of the input / output port, crosstalk to the other input / output port is −25 dB or less. An optical transmission system comprising the optical switch device according to claim 1.

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